Methods of forming an abrasive slurry and methods for chemical-mechanical polishing

ABSTRACT

Methods of forming a slurry and methods of performing a chemical mechanical polishing (CMP) process utilized in manufacturing semiconductor devices, as described herein, may be performed on semiconductor devices including integrated contact structures with ruthenium (Ru) plug contacts down to a semiconductor substrate. The slurry may be formed by mixing a first abrasive, a second abrasive, and a reactant with a solvent. The first abrasive may include a first particulate including titanium dioxide (TiO 2 ) particles and the second abrasive may include a second particulate that is different from the first particulate. The slurry may be used in a CMP process for removing ruthenium (Ru) materials and dielectric materials from a surface of a workpiece resulting in better WiD loading and planarization of the surface for a flat profile.

PRIORITY CLAIM AND CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.62/737,502, filed on Sep. 27, 2018, which application is herebyincorporated herein by reference.

BACKGROUND

Generally, contacts down to a semiconductor substrate may be made byfirst forming a dielectric layer and then forming openings within thedielectric layer to expose the underlying substrate where contact isdesired to be made. Once the openings have been formed, a barrier layermay be formed within the openings and conductive material may be used tofill the remainder of the openings using, e.g., a plating process. Thisplating process usually fills and overfills the openings, causing alayer of the conductive material to extend up beyond the dielectriclayer.

A chemical mechanical polish (CMP) may be performed to remove the excessconductive material and the barrier layer from outside of the openingsand to isolate the conductive material and the barrier layer within theopenings. For example, the excess conductive material may be contactedto a polishing pad, and the two may be rotated in order to grind excessconductive material away. This grinding process may be assisted by theuse of a CMP slurry, which may contain chemicals and abrasives that canassist in the grinding process and help remove the conductive material.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a substrate with an overlying dielectric layer andcontact openings overfilled with a conductive material, in accordancewith some embodiments.

FIG. 2 illustrates a chemical mechanical polishing (CMP) system, inaccordance with some embodiments.

FIGS. 3A-3B illustrate a bulk CMP process and result, in accordance withsome embodiments.

FIGS. 4A-4B illustrate a buffing CMP process and result, in accordancewith some embodiments.

FIG. 5 illustrates examples of some abrasives used to form a slurry, inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The embodiments will be described with respect to embodiments in aspecific context, namely slurry abrasives and chemical mechanicalpolishing (CMP) processes utilized in manufacturing semiconductordevices including integrated contact structures with ruthenium (Ru) plugcontacts down to a semiconductor substrate. The embodiments may also beapplied, however, to other metal contact structures and other CMPprocesses.

With reference now to FIG. 1, there is shown a workpiece 100 including asubstrate 101, a first inter-layer dielectric (ILD) layer 102,source/drain plugs 106, active devices 125, a second inter-layerdielectric (ILD) layer 103, a second conductive fill material 105, afirst target level 309 of a bulk CMP material removal process, and asecond target level 409 of a buff CMP material removal process. However,any number of other suitable material layers may be included in theworkpiece 100 and any desired number of target levels of any number ofsuitable CMP material removal processes may be applied.

The substrate 101 may comprise bulk silicon, doped or undoped, or anactive layer of a silicon-on-insulator (SOI) substrate. Generally, anSOI substrate comprises a layer of a semiconductor material such assilicon, germanium, silicon germanium, SOI, silicon germanium oninsulator (SGOI), or combinations thereof. Other substrates that may beused include multi-layered substrates, gradient substrates, or hybridorientation substrates.

In addition, the substrate 101 may include active devices 125 formedwithin the substrate 101. As one of ordinary skill in the art willrecognize, a wide variety of active devices 125 and passive devices (notshown) such as transistors, capacitors, resistors, combinations ofthese, and the like may be used to generate the desired structural andfunctional requirements of the design for a semiconductor device and maybe formed using any suitable methods. For example, in some embodimentsthe active devices 125 may be FinFET devices, wherein fins ofsemiconductor materials are formed with gate stacks over fins of theFinFET devices with shallow trench isolation (STI) regions formedbetween fins and with source/drain regions formed within the fins onopposite sides of the gate stacks. The STI regions and source/drainregions are not separately illustrated for clarity.

The first ILD layer 102 may be formed over the substrate 101 in order toprovide electrical isolation between the substrate 101 and overlyingmetallization layers (e.g., intermetal dielectrics (IMD), redistributionlayers, back end of the line (BEOL) metallization layers, or the like).The first ILD layer 102 may be a dielectric film formed, for example, bychemical vapor deposition, sputtering, or any other methods known andused in the art for forming an ILD. The first ILD layer 102 may have aplanarized surface and may be comprised of dielectric materials such asdoped or undoped silicon oxide, silicon nitride, doped silicate glass,other high-k materials, combinations of these, or the like, could beutilized. In an embodiment the first ILD layer 102 may comprise amaterial such as boron phosphorous silicate glass (BPSG), although anysuitable dielectrics may be used for either layer. The first ILD layer102 may be formed using a process such as CVD, PVD, PECVD, althoughother processes, such as LPCVD, may also be used.

After formation, the first ILD layer 102 may be planarized using, e.g.,a chemical mechanical polish (CMP) process in order to planarize thefirst ILD layer 102. However, any other suitable planarization processmay be used to reduce the first ILD layer 102 to the desired height andto provide a flat profile for the first ILD layer 102.

Once the first ILD layer 102 has been formed, source/drain plugs 106 maybe formed through the first ILD layer 102 to provide some of theelectrical connections to the active devices 125. In an embodiment theformation of the source/drain plugs 106 may be initiated by firstforming contact plug openings through the first ILD layer 102 to exposecontact areas of the source/drain regions. For example, the exposedcontact areas may be epitaxial regions in the source/drain regions ofthe active devices 125.

In an embodiment, the contact plug openings may be formed using asuitable photolithographic masking and etching process. However, anysuitable process may be used to form the openings. Once the contact plugopenings have been formed in the first ILD layer 102, a formation of afirst glue layer (not separately illustrated in FIG. 1) may beinitiated. In an embodiment the first glue layer is utilized to helpadhere the rest of the source/drain plugs 106 to the underlyingstructure and may be, e.g., ruthenium, tungsten, titanium nitride,tantalum nitride, or the like formed using a process such as CVD, plasmaenhanced chemical vapor deposition (PECVD), physical vapor deposition(PVD), atomic layer deposition (ALD), and the like or the like.

Once the first glue layer has been formed, a first conductive fillmaterial may be formed to fill the contact openings in the first ILDlayer 102 and may be formed in contact with the first glue layer toprovide an electrical connection to the active devices 125 formed withinthe substrate 101. In an embodiment the material of the first conductivefill material is ruthenium (Ru), although any other suitable material,such as tungsten, tungsten nitride, aluminum, copper, silver, gold,rhodium, molybdenum, nickel, cobalt, cadmium, zinc, alloys of these,combinations thereof, and the like, may be utilized. The firstconductive fill material may be formed within the contact openings usinga process such as plating (e.g., electroplating, electroless-plating),physical vapor deposition (PVD), chemical vapor deposition (CVD),plasma-enhanced chemical vapor deposition (PECVD), atomic layerdeposition (ALD), combinations of these, or the like. In an embodiment,the first conductive fill material may be deposited in the contactopenings formed through the first ILD layer 102 to fill and/or overfillsthe contact openings.

Once the first conductive fill material has been formed, the workpiece100 may be subjected to one or more subsequent CMP removal processes(discussed in greater detail below) are used to planarize the first gluelayer and/or the first conductive fill material with the first ILD layer102. The CMP removal processes are discussed in greater detail belowwith regard to the remaining figures. Once planarized, the surface ofthe first ILD layer 102 and contact areas of the first conductive fillmaterial are exposed at the outer surface of the workpiece 100. As such,source/drain plugs 106 are formed from remaining portions of the firstconductive fill material which are isolated between sections of thefirst ILD layer 102, wherein contact areas of the source/drain plugs 106are exposed and planarized with the first ILD layer 102 at the outersurface of the workpiece 100. Furthermore, any number of suitable CMPremoval processes may be applied to the workpiece 100. According to someembodiments, the S/D plug 106 may be formed to a first width W₁ at asurface of the first ILD layer 102 opposite the substrate 101. In anembodiment, the first width W₁ may be between about 100 nm and about 1nm, such as about 20 nm. However, any suitable width may be used.

Once the source/drain plugs 106 have been formed in the first ILD layer102, the second ILD layer 103 is formed over the planarized surface ofthe first ILD layer 102 covering the contact areas of the source/drainplugs 106. The contact plugs 107 are formed in second ILD layer 103 toelectrically connect the source/drain plugs 106 of the active devices125. As such, the second ILD layer 103 provides electrical isolationbetween the first ILD layer 102 and overlying metallization layers(e.g., intermetal dielectrics (IMD), redistribution layers, back end ofthe line (BEOL) metallization layers, or the like). The second ILD layer103, contact plug openings in the second ILD layer 103 used to form thecontact plugs 107, and the contact plugs 107 may be formed using any ofthe materials, the deposition processes, the photolithographic maskingand etching processes, and the planarization processes suitable forforming the first ILD layer 102, the contact openings in the first ILDlayer 102, and the source/drain plugs 106, as set forth above.

According to an embodiment, the second ILD layer 103 and the contactplugs 107 formed within the second ILD layer 103 are formed using thesame materials and the same processes for forming the source/drain plugs106 in the first ILD layer 102, as set forth above. However, thematerials, the deposition process, and the planarization process used toform the first ILD layer 102 and the second ILD layer 103 may also bedifferent and any suitable dielectrics may be used for either layer.According to some embodiments, the second ILD layer 103 may be formed toa thickness of between about 5 nm and about 100 nm, such as about 50 nm.However, any suitable thickness may be used.

Once the second ILD layer 103 has been formed, contact plug openings andthe contact plugs 107 may be formed through the second ILD layer 103 toelectrically connect the source/drain plugs 106 of the active devices125 formed in the substrate 101. In an embodiment, the formation of thecontact plugs 107 may be initiated by first forming contact plugopenings through the second ILD layer 103 to expose contact areas (notshown) of either the source/drain plugs 106, and/or gate electrodes ofthe active devices 125 isolated within the first ILD layer 102. Inanother embodiment, the contact areas at the surface of the first ILDlayer 102 may be contacts of a redistribution layer (not shown) that areelectrically coupled to either the source/drain regions or else the gateelectrodes of the active devices 125 isolated within the first ILD layer102. The contact plug openings may be formed to a first width W₁ at asurface of the second ILD layer 103 opposite the first ILD layer 102.According to some embodiments, the first width W₁ may be between about100 nm and about 1 nm, such as about 20 nm. However, any suitable widthmay be used.

Once the contact plug openings have been formed in the second ILD layer103, formation of a second glue layer (not separately illustrated inFIG. 1) utilized to help adhere the rest of the contact plugs 107 to theunderlying structure and the second conductive fill material 105 overthe second glue layer may be formed to fill the contact plug openings inthe second ILD layer 103 to provide an electrical connection to thefirst ILD layer 102. According to embodiments, the second glue layer andthe second conductive fill material 105 may be formed using anymaterials and any processes suitable for forming the first glue layerand for depositing the first conductive fill material to form thesource/drain plugs 106 in the first ILD layer 102, as set forth above.According to an embodiment, the first glue layer and the second gluelayer are formed using the same material (e.g., ruthenium (Ru)) and aredeposited using the same process (e.g., plasma enhanced chemical vapordeposition (PECVD)), although the materials and processes may also bedifferent. According to an embodiment, the first conductive fillmaterial and the second conductive fill material 105 are formed usingthe same material (e.g., ruthenium (Ru)) and are deposited using thesame process such as plating (e.g., electroplating,electroless-plating), although the materials and processes may also bedifferent.

In an embodiment, the second conductive fill material 105 may bedeposited in the contact openings formed through the second ILD layer103 and the deposition of the second conductive fill material 105 may becontinued until the second conductive fill material 105 fills thecontact openings and extends above the second ILD layer 103 to a firstheight H₁ above the first ILD layer 102. In an embodiment, the firstheight H₁ may be between about 10 nm and about 200 nm, such as about 60nm. However, any suitable height may be used.

Once the second conductive fill material 105 has been formed, theworkpiece 100 is prepared for subsequent CMP removal processes. In anembodiment, the workpiece 100 may be subjected to a first CMP removalprocess to remove a portion of the second conductive fill material 105from an outer surface of the workpiece 100 above the second ILD layer103 to a first target level 309 at a first depth D₁. In an embodiment,the first depth D₁ may be between about 100 nm and about 5 nm, such asabout 10 nm. Accordingly, the portion of the workpiece 100 above thefirst ILD layer 102 may be reduced, for example, from the first heightH₁ to a second height H₂. In an embodiment, the second height H₂ may bebetween about 100 nm and about 5 nm, such as about 50 nm. However, anysuitable heights may be used. Furthermore, once the workpiece is reducedto the first target level 309, a surface of the second ILD layer 103 andcontact areas of the second conductive fill material 105 that areisolated between sections of the second ILD layer 103 may be exposed atthe outer surface of the workpiece 100.

Once the first CMP removal process has been performed, the workpiece 100may be subjected to a second CMP removal process, according to someembodiments, for example, to planarize or smooth an outer surface of theworkpiece 100 and/or to further reduce the height of the workpiece 100.According to an embodiment, the second CMP removal process may beperformed, for example to remove portions of the second ILD layer 103and portions of the second conductive fill material 105 isolated betweensections of the second ILD layer 103 from an outer surface of theworkpiece 100 above the first ILD layer 102 to a the second target level409 at a second depth D₂. In an embodiment, the second depth D₂ may bebetween about 50 nm and about 1 nm, such as about 30 nm. Accordingly,the portion of the workpiece 100 above the first ILD layer 102 may bereduced, for example, from the second height H₂ to a third height H₃. Inan embodiment, the third height H₃ may be between about 99 nm and about4 nm, such as about 20 nm. However, any suitable heights may be used.Furthermore, once the workpiece is reduced to the second target level409, a surface of the second ILD layer 103 and contact areas of thesecond conductive fill material 105 that are isolated between sectionsof the second ILD layer 103 may be exposed at the outer surface of theworkpiece 100. Although two CMP removal processes and two target levelsare described, any desired number of target levels and any number ofsuitable CMP removal processes may be applied to the workpiece 100.

FIG. 2 illustrates a CMP system 200 which may be used to remove theexcess conductive fill material 105 and to remove the excess materialsof the second ILD layer 103, thereby isolating the second conductivefill material 105 in the contact openings of the second ILD layer 103.The CMP system 200 may include loadlocks 201, cleaning station 205, ahigh-rate platen 207, and a buffing platen 211. The loadlocks 201 may beused for loading the workpiece 100 into the CMP system 200, and thenunloading the workpiece 100 once the CMP process has been completed. Thehigh-rate platen 207 may be used for polishing and removing the secondconductive fill material 105 with a relatively high polishing rate, suchas a bulk polishing rate, while the buffing platen 211 may be used forpolishing and removing materials of the second ILD layer 103 and also tofix defects and scratches that may occur during the removal of thesecond conductive fill material 105.

FIGS. 3A-3B illustrate the process and result of a bulk CMP process 300performed on the workpiece 100. In an embodiment, the workpiece 100 maybe loaded into the CMP system 200 through the loadlocks 201 and passedto the high-rate platen 207 for a bulk removal of the second conductivefill material 105 (see FIG. 2). Once at the high-rate platen 207 (asillustrated in FIG. 3A), the workpiece 100 may be connected to a firstcarrier 301, which faces the surface of the second conductive fillmaterial 105 coincident the outer surface of the workpiece 100 towards afirst polishing pad 303 connected to the high-rate platen 207.

The first polishing pad 303 may be a hard polishing pad that may beutilized for a relatively quick removal of the second conductive fillmaterial 105. In an embodiment the first polishing pad 303 may be asingle layer or composite layer of materials such as polyurethane orpolyurethane mixed with fillers, and may have a hardness of about 50 orgreater on the Shore D Hardness scale. The surface of the firstpolishing pad 303 may be a roughened surface with micropores within it.However, any other suitable polishing pad may be used to remove a bulkof the second conductive fill material 105 from the surface of thesecond ILD layer 103 (as illustrated in FIG. 3B).

During the bulk CMP process 300 the first carrier 301 may press thesurface of the second conductive fill material 105 against the firstpolishing pad 303. The workpiece 100 and the first polishing pad 303 areeach rotated against each other, either in the same direction or elsecounter-rotated in opposite directions. By rotating the first polishingpad 303 and the workpiece 100 against each other, the first polishingpad 303 mechanically grinds away the second conductive fill material105, thereby effectuating a removal of the second conductive fillmaterial 105. Additionally, in some embodiments the first carrier 301may move the workpiece 100 back and forth along a radius of the firstpolishing pad 303.

Additionally, the mechanical grinding of the first polishing pad 303 maybe assisted through the use of a bulk CMP slurry 305, which may bedispensed onto the first polishing pad 303 through a slurry dispensingsystem 307. In an embodiment the bulk CMP slurry 305 may comprise areactant, an abrasive, a surfactant, and a solvent.

The reactant in the bulk CMP slurry 305 may be a chemical that willchemically react with the second conductive fill material 105 in orderto assist the first polishing pad 303 in grinding away the secondconductive fill material 105, such as an oxidizer. In an embodiment inwhich the second conductive fill material 105 is ruthenium (Ru), a firstreactant 313 may be a weak oxidizer (e.g., K₃Fe(CN)₆, FeNO₃, or Br),such as, e.g., hydrogen peroxide (H₂O₂), although any other suitablereactant, such as guanidine, an amine, pyridine, combinations of these,and the like, that will aid in the removal of the second conductive fillmaterial 105 may also be utilized. The first reactant 313 may be betweenabout 20% by weight to about 0% by weight of the bulk CMP slurry 305,such as about 5% by weight of the bulk CMP slurry 305.

The abrasive 311 in the bulk CMP slurry 305 may be any suitableparticulate that, in conjunction with the first polishing pad 303, aidsin the removal of the second conductive fill material 105. In anembodiment the abrasive 311 may comprise a first particulate such astitanium dioxide (TiO₂) with a particle size of between about 300 nm andabout 10 nm, such as 150 nm. Titanium dioxide (TiO₂) abrasives have arelatively high polish rate for ruthenium oxide (RuO₂) and a relativelylow polish rate for dielectric materials (e.g., oxide film). Therefore,titanium dioxide (TiO₂) can polish ruthenium (Ru) using the relativelyweak oxidizers (e.g., H₂O₂) which may prevent tool corrosion and can besafer for users in the environment and can be more friendly to theenvironment overall because relatively weak oxidizers (e.g., H₂O₂) mayreact with ruthenium such that non-toxic gases, for example, rutheniumhydroxide (Ru(OH)₃), are produced as a byproduct 315 instead of toxicgases (e.g., ruthenium tetroxide (RuO₄)).

Additionally, the abrasive 311 may be a hybrid abrasive including acombination of two or more particulates. For example, in addition to thefirst particulate, the abrasive 311 may also comprise a secondparticulate such as silica (e.g., silicon dioxide (SiO₂)) with aparticle size of between about 300 nm and about 10 nm, such as 150 nm.Silicon dioxide (SiO₂) abrasives have a relatively low polish rate forruthenium oxide (RuO₂) and a relatively high polish rate for dielectricmaterials (e.g., oxide film) as compared to some other abrasives (e.g.,titanium dioxide (TiO₂)).

In still other embodiments, the second particulate may comprise alumina(e.g., aluminum oxide (Al₂O₃)) with a particle size of between about 300nm and about 10 nm, such as 150 nm. However, any other suitableabrasive, such as cerium oxide, polycrystalline diamond, polymerparticles such as polymethacrylate or polymethacryclic, combinations ofthese, or the like, may also be utilized and are fully intended to beincluded within the scope of the embodiments.

Furthermore, in the case where the abrasive 311 is a hybrid abrasive,the combination of particulates may be provided in different ratios ofone particulate to another particulate. For example, the abrasive 311may comprise a ratio of the first particulate (e.g., titanium dioxide(TiO₂)) to the second particulate (e.g., silicon dioxide (SiO₂)). In anembodiment, the abrasive 311 may have a ratio of titanium dioxide tosilicon dioxide of 0 to 1 (or a ratio of titanium dioxide to aluminumoxide of 0 to 1) and may include 10 parts by volume of titanium dioxide(TiO₂) particles to 10 parts by volume of silicon dioxide (SiO₂)particles. For example, when polishing a material comprising rutheniumoxide (RuO₂) layers, the abrasive 311 may be chosen, according to someembodiments, to comprise a ratio of TiO₂ particles to SiO₂ particles tobe within a range of between about 10,000 TiO₂/SiO₂ by volume and about0.0001 TiO₂/SiO₂ by volume, such as about 1 TiO₂/SiO₂ by volume.However, any suitable ratio and any other suitable abrasive may beutilized and are fully intended to be included within the scope of theembodiments.

The surfactant may be utilized to help disperse the first reactant 313and the abrasive 311 within the bulk CMP slurry 305 and also prevent theabrasive 311 from agglomerating during the bulk CMP process 300. In anembodiment the surfactant may include sodium salts of polyacrylic acid,potassium oleate, sulfosuccinates, sulfosuccinate derivatives,sulfonated amines, sulfonated amides, sulfates of alcohols, alkylanylsulfonates, carboxylated alcohols, alkylamino propionic acids,alkyliminodipropionic acids, combinations of these, or the like.However, these embodiments are not intended to be limited to thesesurfactants, as any suitable surfactant may be utilized as the firstsurfactant. In an embodiment, the concentration of the surfactant in thebulk CMP slurry 305 may be between about 20% by volume and about 0% byvolume, such as about 5% by volume of the bulk CMP slurry 305.

The remainder of the bulk CMP slurry 305 may be a solvent that may beutilized to combine the first reactant 313, the abrasive 311, and thesurfactant and allow the mixture to be moved and dispersed onto thefirst polishing pad 303. In an embodiment the solvent of the bulk CMPslurry 305 may be a first solvent such as deionized water or an alcohol.However, any other suitable solvent may also be utilized as the firstsolvent. In an embodiment, the concentration of the solvent in the bulkCMP slurry 305 may be between about 99% by volume and about 70% byvolume, such as about 95% by volume of the bulk CMP slurry 305.

In some embodiments, the bulk CMP slurry 305 may comprise otheradditives. For example, the bulk CMP slurry 305 may comprise a firstadditive that is a corrosion inhibitor. However, any other suitableadditives may be utilized.

Embodiments of the bulk CMP slurry 305 disclosed herein refer tospecific examples of reactants, abrasives, surfactants, solvents, and/orcorrosion inhibitors. However, it is to be understood that any suitablereactant, abrasive, surfactant, solvent, and/or corrosion inhibitor maybe utilized as the first reactant 313, the abrasive 311, the firstsurfactant, the first solvent, and/or the other additives withoutdeparting from the spirit and scope of the embodiments described herein.

Once mixed, the bulk CMP slurry 305 may be dispensed onto the firstpolishing pad 303 by the slurry dispensing system 307. In an embodiment,the bulk CMP slurry 305 may be dispensed onto the first polishing pad303 at a rate of between about 2000 sccm and about 100 sccm. Inaddition, the workpiece 100 may be forced into contact with the firstpolishing pad 303 by the first carrier 301 pressing the surface of theworkpiece 100 against the first polishing pad 303. In an embodiment ofthe bulk CMP process 300, the first carrier 301 may push the workpiece100 onto the high-rate platen 207 with a force of between about 600 hpato about 30 hpa, such as about 250 hpa. As the high-rate platen 207rotates the first polishing pad 303 underneath the workpiece 100, thebulk CMP slurry 305 is applied to the exposed surface of the secondconductive fill material 105 of the workpiece 100 in order to assist inthe removal of the second conductive fill material 105. In anembodiment, during the bulk CMP process 300, the high-rate platen 207rotates at a speed of between about 20 rpm to about 400 rpm and thefirst carrier 301 rotates the workpiece 100 at a speed of about 20 rpmto about 400 rpm.

By rotating the first polishing pad 303 and the workpiece 100 againsteach other using the bulk CMP slurry 305, the first polishing pad 303along with the assistance of the abrasive 311 in the bulk CMP slurry 305mechanically grind away the second conductive fill material 105, therebyeffectuating a removal of the second conductive fill material 105 at afirst rate of removal. In an embodiment, the first rate of removal ofthe second conductive fill material 105 is between about 10 Å per minuteand about 2000 Å per minute, such as about 200 Å per minute. FIG. 3Billustrates a result after an embodiment of the bulk CMP process 300 hasbeen performed in which the excess material of the second conductivefill material 105 has been removed from the surface of the workpiece100.

Additionally, beyond just physically removing a portion of the secondconductive fill material 105, the bulk CMP process 300 with the firstreactant 313 and the abrasive 311 may react with material of the secondconductive fill material 105 to form a sacrificial layer (not shown)along the exposed surface of the second conductive fill material 105.The sacrificial layer may then be removed by the grinding effect of thefirst polishing pad 303 along with the assistance of the abrasive 311within the bulk CMP slurry 305. In particular, the first reactant 313and the abrasive 311 may react with the surface of the second conductivefill material 105 to effectively boost the rate of removal of the secondconductive fill material 105. In an embodiment in which the secondconductive fill material 105 is ruthenium (Ru) and the first reactant313 is an oxidizer (e.g., hydrogen peroxide (H₂O₂)), the first reactant313 may react with the ruthenium (Ru) to form a material of thesacrificial layer (e.g., ruthenium oxide) as illustrated in Equation 1.Ru+H₂O₂RuOx  Eq. 1.

FIG. 3B shows, for example, the result of the bulk CMP process 300performed on the workpiece 100 to remove a bulk of the second conductivefill material 105 extending above the surface of the second ILD layer103. In an embodiment, a portion of the second conductive fill material105 is removed during the bulk CMP process 300 such that the workpiece100 is reduced from the first height H₁ (shown in FIG. 1) to the secondheight H₂ and such that a remaining portion of the workpiece 100,between the first target level 309 and the substrate 101, is leftintact.

In addition, during the removal of the second conductive fill material105, the materials of the bulk CMP slurry 305 and materials of thesecond conductive fill material 105 react such that a byproduct 315 maybe formed. In some reactions between materials, the byproduct 315 may beformed as a vapor while in other reactions, the byproduct 315 may have aform different than a vapor (e.g., liquid, or solid). Furthermore, insome reactions between materials, the byproduct 315 may be formed as atoxic gas while in other reactions the byproduct 315 may be formed as anon-toxic gas.

In a specific embodiment, in which the second conductive fill material105 is ruthenium (Ru), the first reactant 313 is hydrogen peroxide(H₂O₂), and the abrasive 311 is titanium dioxide (TiO₂), the byproduct315 may be formed as ruthenium hydroxide (Ru(OH)₃) during the bulkremoval of the second conductive fill material 105. The titanium dioxide(TiO₂) and the hydrogen peroxide (H₂O₂) may react with the ruthenium(Ru) to form ruthenium hydroxide (Ru(OH)₃), a non-toxic gas, asillustrated by Equation 2 and Equation 3.

$\begin{matrix}\left. {{Ru} + {TiO}_{2} + {H_{2}O_{2}}}\rightarrow{{Ti} - O - {{Ru}\mspace{14mu}{or}\mspace{14mu}{Ru}} - O - O - {{Ti}.}} \right. & {{Eq}.\mspace{14mu} 2} \\{{{Ru}^{3 +}\mspace{14mu}{OH}^{-}}\overset{{p\; H} = {8\sim 11}}{\rightarrow}{{{Ru}({OH})}^{3}.}} & {{Eq}.\mspace{14mu} 3}\end{matrix}$In the instance that the byproduct 315 is formed as ruthenium hydroxide(Ru(OH)₃), this byproduct 315 is not considered to be toxic (e.g.,non-toxic byproduct) and does not have the undesirable effectsassociated with toxic byproducts. In the instant case where thebyproduct 315 is formed as ruthenium hydroxide (Ru(OH)₃), the processmay allow for more environmentally friendly gasses to be emitted thatare safer for the environment and safer for users in the environment.Thus, non-toxic byproducts of some embodiments of the CMP process mayprovide a safer environment for the users to work in, may allow forextended longevity of tool capabilities and/or may prevent corrosion ofother metals within the surrounding environment.

In a specific embodiment in which the second conductive fill material105 comprises ruthenium (Ru) and the abrasive 311 comprises silicondioxide (SiO₂), using a first reactant 313 that comprises a relativelyweak oxidizer (e.g., hydrogen peroxide H₂O₂) avoids the production of atoxic byproduct (e.g., ruthenium tetroxide (RuO₄)) which may be formedduring the bulk CMP process 300 when using a first reactant thatcomprises a relatively strong oxidizer (e.g., iodate (IO₃—) or periodate(IO₄—)) such as sodium periodate NaIO₄. Ruthenium tetroxide (RuO₄) gasis considered to be a toxic gas that may be harmful to users in theenvironment and may have other undesirable effects, such as, destroyingtool capabilities and/or corroding other metals within the surroundingenvironment.

FIG. 3B illustrates the result of the bulk CMP process 300. Asillustrated, the bulk CMP process 300 uses the abrasive 311 and thefirst reactant 313 to aid in the removal of a bulk of the secondconductive fill material 105 from the outer surface of the workpiece 100to the first target level 309. As further illustrated in FIG. 3B, theresulting structure of the workpiece 100 includes contact plugs 107formed from the second conductive fill material 105 isolated within thecontact openings of the second ILD layer 103 with outer surfaces of thesecond conductive fill material 105 of the contact plugs 107 and outersurfaces of the second ILD layer 103 being coincident the outer surfaceof the workpiece 100. In an embodiment, the outer surfaces of the secondconductive fill material 105 form contact areas (not illustrated) of thecontact plugs 107 isolated within the second ILD layer 103, the contactareas having a width substantially equal to the first width W₁. However,any suitable widths may be used. In addition, during the bulk CMPprocess, the byproduct 315 may be formed from the chemical reactionsbetween materials of the second conductive fill material 105, thematerials of the abrasive 311, and the first reactant 313.

However, as one of ordinary skill in the art will recognize, the abovedescription of removing the excess conductive fill material 105 abovethe first target level 309 in a single processing step is merely anillustrative example and is not intended to be limiting upon theembodiments. Any number of removal processes and any number of platensmay be utilized to remove the second conductive fill material 105, andall such combinations are fully intended to be included within the scopeof the embodiments.

FIGS. 4A-4B illustrate the process and result of a buffing CMP process400 performed on the workpiece 100. In an embodiment the workpiece 100may be removed from the high-rate platen 207 and may be transferred tothe buffing platen 211 (see FIG. 2), where the workpiece 100 may beattached to a second carrier 404, which also faces the outer surfaces ofthe second conductive fill material 105 and outer surfaces of the secondILD layer 103 being coincident the outer surface of the workpiece 100towards a second polishing pad 402 on the buffing platen 211. The secondpolishing pad 402 may perform a similar CMP process as the high-rateplaten 207, with the second polishing pad 402 grinding away the secondconductive fill material 105 of the contact plugs 107 and the materialof the second ILD layer 103 from the outer surface of the workpiece 100to the second target level 409. In addition, the buffing CMP process 400may include a buffing CMP slurry 405 being dispersed by a buffing slurrydispenser 407 to aid in the grinding process. In an embodiment thebuffing CMP slurry 405 may comprise a reactant, an abrasive, asurfactant, and a solvent.

In some embodiments, the buffing CMP slurry 405 may include one or moreof the first reactant 313, the abrasive 311, the first surfactant, andthe solvent that is used in the bulk CMP slurry 305 for the bulk CMPprocess 300. However, any suitable reactant, abrasive, surfactant,solvent, and/or corrosion inhibitor may be utilized as the secondreactant, the second abrasive, the second surfactant, the secondsolvent, and/or the corrosion inhibitor without departing from thespirit and scope of the embodiments described herein.

Once mixed, the buffing CMP slurry 405 may be dispensed onto the secondpolishing pad 402 by the buffing slurry dispenser 407. In an embodiment,the buffing CMP slurry 405 may be dispensed onto the second polishingpad 402 at a rate of between about 2000 sccm and about 100 sccm. Inaddition, the workpiece 100 may be forced into contact with the secondpolishing pad 402 by the second carrier 404 pressing the surface of theworkpiece 100 against the second polishing pad 402. In an embodiment ofthe buffing CMP process 400, the second carrier 404 may push theworkpiece 100 onto the buffing platen 211 with a force of between about500 hpa to about 50 hpa, such as about 200 hpa. As the buffing platen211 rotates the second polishing pad 402 underneath the workpiece 100,the buffing CMP slurry 405 is applied to the exposed surface of theworkpiece 100 in order to assist in the removal of the second conductivefill material 105 and the materials of the second ILD layer 103. In anembodiment, during the buffing CMP process 400, the buffing platen 211rotates at a speed of between about 30 rpm to about 300 rpm while thesecond carrier 404 rotates the workpiece 100 at a speed of about 30 rpmto about 300 rpm.

By rotating the second polishing pad 402 and the workpiece 100 againsteach other using the buffing CMP slurry 405, the second polishing pad402 along with the assistance of the abrasive 311 in the buffing CMPslurry 405 mechanically grinds away the second conductive fill material105 of the contact plugs 107 and the dielectric material of the secondILD layer 103, thereby effectuating a removal of excess materials of thesecond conductive fill material 105 and effectuating a removal of excessmaterials of the second ILD layer 103 at comparable rates of removal. Inan embodiment, the buffing CMP process 400 may remove a portion of thesecond conductive fill material 105 of the contact plugs 107 at a firstcomparable rate of removal and a portion of the second ILD layer 103 ata second comparable rate of removal. In an embodiment, the firstcomparable rate of removal of the second conductive fill material 105 ofthe contact plugs 107 is between about 10 Å per minute and about 2000 Åper minute, such as about 200 Å per minute and the second comparablerate of removal of the excess materials of the second ILD layer 103 isbetween about 10 Å per minute and about 2000 Å per minute, such as about200 Å per minute.

In an embodiment in which the second conductive fill material 105 of thecontact plugs 107 is ruthenium (Ru) and the materials of the second ILDlayer 103 include an oxide (e.g., oxide film), a second reactant 413 mayreact with the ruthenium (Ru) of the second conductive fill material 105and may have little to no reaction with the oxide of the materials ofthe second ILD layer 103. In this manner, a sacrificial layer ofruthenium oxide (RuO₂) (not shown) is formed along exposed surfaces ofthe second conductive fill material 105 and the oxide of the materialsof exposed surfaces of the second ILD layer 103 remain relativelyunchanged by the second reactant 413. The ruthenium oxide and the oxideof the materials of the second ILD layer 103 may then be removed by thegrinding effect of the second polishing pad 402 along with theassistance of the abrasive 311 within the buffing CMP slurry 405.

In an embodiment the second polishing pad 402 may be a soft buffing padwhich may remove the second conductive fill material 105 and thematerials of the second ILD layer 103 at a slower and more controlledrate than the first polishing pad 303 removed the second conductive fillmaterial 105 while also buffing and eliminating defects and scratchesthat may have been caused by the bulk CMP process 300. In an embodimentthe second polishing pad 402 may be rotated relative to the workpiece100 while the buffing CMP slurry 405 is dispensed on the secondpolishing pad 402.

In an embodiment, the ruthenium oxide of the exposed portions of thesecond conductive fill material 105 may then be removed by the grindingeffect of the second polishing pad 402 along with the assistance of theabrasive 311 within the buffing CMP slurry 405 at an effective boostedremoval rate. The materials and the ratios selected for the plurality ofabrasives mixed in the buffing CMP slurry 405 may be selected to have adesired first removal rate for the ruthenium (Ru) of the plug materialand may have a desired second removal rate for the dielectric materialof the second ILD layer 103. In some embodiments, the second removalrate may be different from the first removal rate. In other embodiments,the second removal rate may be comparable to the first removal rate.

In an embodiment, the ruthenium oxide of the exposed portions of thesecond conductive fill material 105 may be removed at a rate comparableto the rate of removal of the dielectric materials along exposedportions of the second ILD layer 103 which may lead to better WiDloading and planarization of a surface for a flat profile. In a hybridabrasive system, the abrasives can perform a chemical reaction with theoxidizer and/or perform a chemical reaction directly with the secondconductive fill material 105 (e.g., ruthenium (Ru)) to produce a freeradical used in a subsequent mechanical polishing process. In addition,ratios between particulates of a hybrid abrasive may be adjustable whichmay allow for the CMP slurry to be fine-tuned and applied on differentfilm schemes and different layouts in all generations of technologyproducts (e.g., N5 node and beyond).

Using this buffing CMP process 400, a removal of the second conductivefill material 105 and a removal of the material of the second ILD layer103 may be performed at a substantially same rate of buffing removal,and the buffing CMP process 400 may be continued until the secondconductive fill material 105 and materials of the second ILD layer 103are removed from the outer surface of the workpiece 100 to the secondtarget level 409. Therefore, using the buffing CMP process 400 avoidsunder polishing of the second conductive fill material 105 and avoidsover-polishing the materials of the second ILD layer 103 of theworkpiece 100. In addition, issues such as pitting and/or dishing of thesecond conductive fill material 105 and under removal of the materialsof the second ILD layer 103 may also be avoided using the buffing CMPprocess 400. Therefore, the buffing CMP process 400 using the buffingCMP slurry 405 with the hybrid abrasive allows for a finely planarizedsurface of the workpiece 100 and allows for better WiD loading (e.g., atestkey thickness through different pattern densities in a die) andplanarization for providing a flat profile.

The buffing CMP process 400 may be continued until the second conductivefill material 105 of the contact plugs 107 and the materials of thesecond ILD layer 103 have been removed from the outer surface of theworkpiece 100 to the second target level 409. In some embodiments, thebuffing CMP process 400 may use a timed or optical end-point detectionto determine when to stop at the second target level 409.

FIG. 4B illustrates a result of the buffing CMP process 400, wherein theexcess conductive fill material 105 of the contact plugs 107 and theexcess materials of the second ILD layer 103 have been removed from theouter surface of the workpiece as desired. In an embodiment, a portionof the second conductive fill material 105 of the contact plugs 107 anda portion of the materials of the second ILD layer 103 are removedduring the buffing CMP process 400 such that the workpiece 100 isfurther reduced from the second height H₂ (shown in FIG. 3B) to thethird height H₃, such that contact areas (not shown) on a first end ofthe contact plugs 107 are exposed at an outer surface of the workpiece100, and such that a remaining portion of the workpiece 100, between thesecond target level 409 and the substrate 101, is left intact.

In addition, during the removal of the second conductive fill material105 of the contact plugs 107, the materials of the buffing CMP slurry405 and materials of the second conductive fill material 105 react suchthat a byproduct 415 may be formed. In some reactions between materials,the byproduct 415 may be formed as a vapor; while in other reactions,the byproduct 415 may have a form different than a vapor (e.g., liquidor solid). Furthermore, in some reactions between materials, thebyproduct 415 may be formed as a toxic gas while in other reactions thebyproduct 415 may be formed as a non-toxic gas, as discussed above withregard to the byproduct 315 of the bulk CMP process 300 and FIG. 3B.However, still other reactions between materials may also occur duringthe buffing CMP process 400 depending on the materials of the buffingCMP slurry 405 and materials of the workpiece 100 resulting in otherbyproducts 415 being formed.

FIG. 4B illustrates the result of the buffing CMP process 400. Asillustrated, the buffing CMP process 400 uses the one or more abrasives311 and the second reactant 413 to aid in the removal of excessmaterials of the second conductive fill material 105 of the contactplugs 107 and the materials of the second ILD layer 103 from the outersurface of the workpiece 100 to the second target level 409. As furtherillustrated in FIG. 4B, the resulting structure of the workpiece 100includes the second conductive fill material 105 of the contact plugs107 isolated within the contact openings of the second ILD layer 103with outer surfaces of the second conductive fill material 105 formingcontact areas of the contact plugs 107 and outer surfaces of the secondILD layer 103 being coincident the outer surface of the workpiece 100.In an embodiment, once the workpiece is reduced to the second targetlevel 409, the contact areas of the contact plugs 107 may have a secondwidth W₂. In an embodiment, the second width W₂ may be between about 100nm and about 1 nm, such as about 20 nm. However, any suitable width maybe used.

However, as one of ordinary skill in the art will recognize, the abovedescription of removing the excess conductive fill material 105 and theexcess materials of the second ILD layer 103 between the first targetlevel 309 and the second target level 409 in a single processing step ismerely an illustrative example and is not intended to be limiting uponthe embodiments. Any number of removal processes and any number ofplatens may be utilized to remove the excess conductive fill material105 and excess materials of the second ILD layer 103, and all suchcombinations are fully intended to be included within the scope of theembodiments.

However, after the buffing CMP process 400, residual particles such asthe abrasive 311 (e.g., titanium oxide (TiO₂)) may be attracted to thesurfaces of the second conductive fill material 105 of the contact plugs107 and/or may be attracted to the surfaces of the second ILD layer 103.This attraction is due to differences between charges of the residualparticles and surface charges of the second conductive fill material 105of the contact plugs 107 and/or surface charges of the materials of thesecond ILD layer 103. Additionally, residual organic material from thebulk CMP process 300 and the buffing CMP process 400 may become attachedto the outer surface of the workpiece 100. This organic material mayoriginate, e.g., as debris from the first polishing pad 303, the secondpolishing pad 402, the first surfactant within the bulk CMP slurry 305,the second surfactant within the buffing CMP slurry 405, pipelinedebris, or other debris from the bulk CMP process 300 and the buffingCMP process 400.

To clean the residual particles and/or the organic material from thesurface of the workpiece 100, a cleaning buffing CMP process (notseparately illustrated) may be performed. In an embodiment the cleaningbuffing CMP process may be performed utilizing the buffing platen 211and the second polishing pad 402 as the buffing CMP process 400described above with respect to FIG. 4A. In a particular embodiment thecleaning buffing CMP process may be performed at the back end of thebuffing CMP process 400 by simply changing the buffing slurry dispenser407 from dispensing the buffing CMP slurry 405 to a cleaning solution.However, as one of ordinary skill in the art will recognize, thecleaning buffing CMP process may also be performed on a separate platenwith a separate polishing pad than the buffing CMP process 400 whilestill remaining within the scope of the embodiments.

According to some embodiments, the cleaning buffing CMP process may beperformed using a cleaning solution that may comprise a cleaningreactant, an optional cleaning surfactant, and the solvent without theuse of abrasives. In an embodiment the cleaning reactant may be achemical which can help to remove the contaminated layer and itscontaminants. For example, excess material debris s of the secondconductive fill material 105 of the contact plugs 107 and excessmaterials of the second ILD layer 103 may be removed from the outersurface of the workpiece 100. In an embodiment, the cleaning reactantmay be phosphoric acid (H₃PO₄), although other suitable chemicals, suchas citric acid or oxalic acid, may also be utilized. The cleaningreactant may be between about 0.1% to about 99% of the cleaningsolution, such as about 5% of the cleaning solution.

In addition, after the cleaning buffing CMP process, the substrate 101may be moved to the cleaning station 205 (see FIG. 2), where anadditional brush cleaning process and/or pencil brush cleaning processmay be performed in order to further clean the surface of the workpiece100. Without the residual particles and residual organic materialspresent during later manufacturing steps, fewer defects may occur,thereby leading to an overall improvement in quality and yield for themanufacturing process.

FIG. 5 illustrates various abrasive coatings that may be selectedindividually or selected in any combination to provide coatings for theabrasive 311 used in mixing the bulk CMP slurry 305 during the bulk CMPprocess 300 (shown and discussed above with regard to FIGS. 3A-3B)and/or to provide coatings for the abrasive 311 used in mixing thebuffing CMP slurry 405 during the buffing CMP process 400 (shown anddiscussed above with regard to FIGS. 4A-4B). The various coatingsillustrated in FIG. 5, include a first coating 503 and a second coating505.

The first coating 503 provided for abrasives 501 may be an organiccoating such as organic polymer, an organic surfactant (e.g., functionalgroups of COOH, OH, NH₃, etc.) that may provide a negative or a positivecharges allowing for the use of attractive and repulsive forces, ifdesired, according to some embodiments. However any other suitableorganic coating may be used as the first coatings 503 and anycombinations of these, or the like, may also be utilized and are fullyintended to be included within the scope of the embodiments.

The second coating 505 provided for abrasives 501, may be an inorganiccoating such as an oxide coating or an aluminum coating (e.g., Ox, Al),according to some embodiments. However any other suitable inorganiccoating may be used as the second coating 505 and any combinations ofthese, or the like, may also be utilized and are fully intended to beincluded within the scope of the embodiments.

In the CMP processes described herein, a ruthenium (Ru) layer (e.g., thesecond conductive fill material 105) may be polished using titaniumoxide (TiO₂) and TiO₂ hybrid abrasives which can provide differentselectivity on ruthenium (Ru) and dielectrics (e.g., oxide films) duringCMP of a surface of a workpiece 100 which leads to better planarizationand WiD loading. In an embodiment, the buffing CMP slurry 405 includes ahybrid abrasive, for example, a first particulate with TiO₂ particlesand a second particulate with SiO₂ particles, that provides a hybridselectivity-balanced system with a removal rate of ruthenium (Ru) thatis comparable to a removal rate of dielectric materials. With thebuffing CMP slurry 405, the hybrid abrasive allows for relatively weakoxidizers (e.g., H₂O₂) to be utilized as the second reactant 413 whichreacts with the ruthenium (Ru) producing a safer byproduct 415 (e.g.,Ru(OH)₃) rather than producing a toxic byproduct (e.g., RuO₄). Thus, asafer environment is maintained for the handlers and an overall morefriendly environmental gas is emitted. Meanwhile, the bulk CMP slurry305 and the buffing CMP slurry 405 using TiO₂ abrasives and/or TiO₂hybrid abrasives, can effectively boost a rate of removal of ruthenium(Ru) and can be adaptable to provide different selectivity of ruthenium(Ru) and to provide different selectivity of dielectrics. Accordingly,these CMP processes described herein can effectively reduce processtime, process cost, and enlarge the process window.

In addition, the slurry may be made to be highly selective for differentfilm schemes and layouts by adjusting a ratio between particulates ofthe hybrid abrasive. Thus, the CMP processes described herein may beapplied to workpieces 100 in the middle end of the line (MEOL) stagesfor structures such as the source/drain plugs 106 and may be adapted andapplied to workpieces in the back end of the line (BEOL) stages forstructures such as the contact plugs 107. Furthermore, the CMP processesdescribed herein may be highly suitable for all generations oftechnologies (e.g., N20, N16, N10, etc.) including N5 node and beyond.

In an embodiment, a method of manufacturing a semiconductor deviceincludes applying a slurry to a surface of a workpiece, wherein at leastone portion of the surface of the workpiece includes ruthenium; forminga ruthenium oxide layer at the at least one portion of the surface ofthe workpiece from a chemical reaction between an oxidizer of the slurryand the ruthenium; removing the ruthenium oxide layer and other portionsof the surface of the workpiece using an abrasive material of theslurry, wherein the abrasive material includes a plurality of differentparticulate materials, at least one of the plurality of particulatematerials including titanium dioxide particles. In an embodiment, themethod includes producing a non-toxic byproduct from chemical reactionsbetween the ruthenium of the at least one portion of the surface of theworkpiece, the titanium dioxide particles of the abrasive material, andthe oxidizer. In an embodiment, the producing a non-toxic byproductincludes producing ruthenium hydroxide. In an embodiment, the removingthe ruthenium oxide layer and the other portions of the surface of theworkpiece includes using a particulate material including silicondioxide as another one of the plurality of particulates of the abrasivematerial. In an embodiment, the forming a ruthenium oxide layer at thesurface of the at least one portion of the surface of the workpieceincludes using hydrogen peroxide as the oxidizer. In an embodiment, theapplying the slurry to the at least one portion of the surface of theworkpiece includes applying the slurry to a surface of a ruthenium plugof a middle end of the line structure, the surface of the ruthenium plugbeing coincident the at least one portion of the surface of theworkpiece.

In an embodiment, a method of manufacturing a semiconductor device, themethod includes dispensing a chemical mechanical polishing (CMP) slurryon an outer surface of a workpiece, the workpiece including a rutheniumlayer with a plurality of ruthenium plugs within an inter-layerdielectric (ILD) layer; using an oxidizer of the CMP slurry to form anoxide layer on surfaces of the ruthenium layer; and performing a CMPremoval of the oxide layer using a first abrasive of the CMP slurry,wherein the first abrasive includes titanium oxide particles and silicondioxide particles. In an embodiment, the performing the CMP removal ofthe oxide layer includes removing excess material of the plurality ofruthenium plugs of the ruthenium layer, and removing excess material ofthe ILD layer from the surface of the workpiece using the CMP slurry,wherein a rate of removal of the oxide layer combined with a rate ofremoval of the excess material of the ruthenium plugs during the CMPremoval is comparable to a rate of removal of the excess material of theILD layer. In an embodiment, performing the CMP removal of the oxidelayer includes: exposing a contact area on an end of one of theplurality of ruthenium plugs at the surface of the workpiece, theexposed contact area being electrically coupled to a finFET devicedisposed at an opposite end of the ruthenium plug from the exposedcontact area. In an embodiment, the CMP slurry includes a secondabrasive including aluminum (II) dioxide particles. In an embodiment,the oxidizer of the CMP slurry is hydrogen peroxide. In an embodiment,the dispensing the CMP slurry on the outer surface of the workpieceincludes dispensing the CMP slurry on an outer surface of a rutheniumlayer of a middle end of the line structure. In an embodiment, themethod further includes producing ruthenium hydroxide as a non-toxicbyproduct from chemical reactions between the ruthenium layer, thetitanium oxide of the first abrasive, and the oxidizer.

In an embodiment, a method of forming a slurry for chemical mechanicalpolishing (CMP) includes mixing a first abrasive with a solvent, thefirst abrasive including a first particulate material including titaniumdioxide particles; mixing a second abrasive with the solvent, the secondabrasive including a second particulate material that is different fromthe first particulate material; and mixing a reactant with the solvent,the reactant including an oxidizer. In an embodiment, the secondparticulate material includes silicon dioxide particles. In anembodiment, the second particulate material includes aluminum oxideparticles. In an embodiment, the oxidizer includes hydrogen peroxide. Inan embodiment, the mixing the first abrasive with the solvent includesproviding an organic coating on the titanium dioxide particles. In anembodiment, the mixing the first abrasive with the solvent includesproviding an inorganic coating on the titanium dioxide particles. In anembodiment, the method further includes mixing a surfactant with thesolvent.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of manufacturing a semiconductor device,the method comprising: applying a slurry to a surface of a workpiece,wherein at least one portion of the surface of the workpiece comprisesruthenium; forming a ruthenium oxide layer at the at least one portionof the surface of the workpiece from a chemical reaction between anoxidizer of the slurry and the ruthenium; removing the ruthenium oxidelayer and other portions of the surface of the workpiece using anabrasive material of the slurry, wherein the abrasive material comprisesa plurality of different particulate materials, at least one of theplurality of different particulate materials comprising titanium dioxideparticles, wherein the applying the slurry to the at least one portionof the surface of the workpiece includes applying the slurry to asurface of a ruthenium plug of a middle end of line structure, thesurface of the ruthenium plug being coincident the at least one portionof the surface of the workpiece; and producing a non-toxic byproductfrom chemical reactions between the ruthenium of the at least oneportion of the surface of the workpiece, the titanium dioxide particlesof the abrasive material, and the oxidizer.
 2. The method of claim 1,wherein the producing a non-toxic byproduct comprises producingruthenium hydroxide.
 3. The method of claim 1, wherein the removing theruthenium oxide layer and the other portions of the surface of theworkpiece includes using a particulate material comprising silicondioxide as another one of the plurality of particulates of the abrasivematerial.
 4. The method of claim 1, wherein the forming a rutheniumoxide layer at the surface of the at least one portion of the surface ofthe workpiece comprises using hydrogen peroxide as the oxidizer.
 5. Themethod of claim 1, wherein at least one of the plurality of differentparticulate materials comprising aluminum (II) dioxide particles.
 6. Themethod of claim 1, wherein the titanium dioxide particles comprise anorganic coating.
 7. A method of manufacturing a semiconductor device,the method comprising: dispensing a chemical mechanical polishing (CMP)slurry on an outer surface of a workpiece, the workpiece including aruthenium layer with a plurality of ruthenium plugs within aninter-layer dielectric (ILD) layer, the ruthenium layer being located ina middle end of line layer and the dispensing of the CMP slurry isdispensed directly onto the ruthenium layer; using an oxidizer of theCMP slurry to form an oxide layer on a surface of the ruthenium layer;and performing a CMP removal of the oxide layer using a first abrasiveof the CMP slurry, wherein the first abrasive includes titanium oxideparticles and silicon dioxide particles.
 8. The method of claim 7,wherein the performing the CMP removal of the oxide layer includesremoving excess material of the plurality of ruthenium plugs of theruthenium layer, and removing excess material of the ILD layer from thesurface of the workpiece using the CMP slurry, wherein a rate of removalof the oxide layer combined with a rate of removal of the excessmaterial of the ruthenium plugs during the CMP removal is comparable toa rate of removal of the excess material of the ILD layer.
 9. The methodof claim 7, wherein performing the CMP removal of the oxide layercomprises: exposing a contact area on an end of one of the plurality ofruthenium plugs at the surface of the workpiece, the exposed contactarea being electrically coupled to a finFET device disposed at anopposite end of one of the ruthenium plugs from the exposed contactarea.
 10. The method of claim 7, wherein the CMP slurry includes asecond abrasive including aluminum (II) dioxide particles.
 11. Themethod of claim 7, wherein the oxidizer of the CMP slurry is hydrogenperoxide.
 12. The method of claim 7, wherein the dispensing the CMPslurry on the outer surface of the workpiece includes dispensing the CMPslurry on the ILD layer.
 13. The method of claim 7, further comprising:producing ruthenium hydroxide as a non-toxic byproduct from chemicalreactions between the ruthenium layer, the titanium oxide particles, andthe oxidizer.
 14. A method of forming and using a slurry for chemicalmechanical polishing (CMP), the method comprising: mixing a firstabrasive with a solvent, the first abrasive comprising a firstparticulate material including titanium dioxide particles; mixing asecond abrasive with the solvent, the second abrasive comprising asecond particulate material that is different from the first particulatematerial; mixing a reactant with the solvent, the reactant comprising anoxidizer; and applying the slurry to a surface of a ruthenium plug of amiddle end of line structure.
 15. The method of claim 14, wherein thesecond particulate material comprises silicon dioxide particles.
 16. Themethod of claim 14, wherein the second particulate material comprisesaluminum oxide particles.
 17. The method of claim 14, wherein theoxidizer comprises hydrogen peroxide.
 18. The method of claim 14,wherein the mixing the first abrasive with the solvent comprisesproviding an organic coating on the titanium dioxide particles.
 19. Themethod of claim 14, wherein the mixing the first abrasive with thesolvent comprises providing an inorganic coating on the titanium dioxideparticles.
 20. The method of claim 14 further comprises mixing asurfactant with the solvent.